Flight trainer



p 1952 H. P. WICKLUND 2,591,752

FLIGHT TRAINER FiledApril 16, 1946 4 Sheets-Sheet 1 j Y I IN VEN TOR.

A TTOPNEY April 8, 1952 H. P. WICKLUND FLIGHT TRAINER Filed April .16, 1946 4 Sheets-Sheet 2 mmvroa HAROLD P W/CKLUAJD BY ATTOPNE Y April 8, 1952 H. P. WICKLUND FLIGHT TRAINER 4 Sheets-Sheet 3 Filed April 16, 1946 INVENTORQ HAROLD Q W/CKLUND ATTORNEY April 8, 1952 Filed April 16, 1946 H. P. W

ICKLUND FLIGHT TRAINER 4 She'efs-Sheet 4 INVENTOR. HAROLD I. WICKL 0ND flTroRn/sy I Patented Apr. 8, 1952 UNITED STATES PATENT OFF-ICE 2,591,752 FLIGHT TRAINER Harold P. Wicklund, United States Navy Application April 16, 1946, Serial No. 662,437-

Claims. (01. 35-12) (Granted under the act of March amended April 30, 1928; 370 O.

is to be subjected to an attack, training in dive bombing, torpedo attack, low-level bombing, carrier-landing technique, and rocket firing.

An object of this invention is to provide such an apparatus and method for conveniently training personnel in the various phases of flying in an airplane and to provide a convenient means for practicing and demonstrating flying.

Another object is to enable a person to view a scale relief map, landfall, or other three-dimensional model, or a plane model such as an aerial photograph from different attitudes and scale altitudes in such a manner that the person can, by the movement of simulated aircraft controls, produce the illusion, with proper relative motion, of actual flying over the actual objects (pertaining to terrain or models) at the corresponding real attitudes or altitudes, such that a realistic impression of flying a real airplane results.

Another object is to provide a compact and relatively simple, inexpensive apparatus for per-' forming the function of several large expensive and complicated training devices hitherto employed.

Further objects and advantages of this invention, as well as its construction, arrangement and operation, are apparent from the following description and claims in connection with the accompanying drawings, in which,

Fig. '1 is a diagrammatic illustration of the training device of this invention,

Fig. 2 is a diagrammatic illustration of an optical system suitable for use in the device shown in Fig. 1,

Fig.3 is a diagrammatic illustration of a masking element used in connection with the optical system of Fig. 2.

Fig. 4 is a diagrammatic illustration of another of the masking elements used in the system of Fig. 2, and

Fig. dis a schematic diagram showing in block form the equipment comprising the computer unit of the device of Fig. 1.

General arrangement 3, 1883, as G. 757) and view through an optical viewing system an area containing a model of terrain in such detail as to produce an effect of realism. As used herein terrain refers to any area of the earth including land and/or water and/or air. The elements of the-optical viewing system are remotely controlled, in response to manipulations of'the mock control elementsv by the pilot in the cockpit, in such manner as to produce an image of the model that simulates and transmits to the pilotthe illusion of seeing an actual view as would be seen from the cockpit of a real plane. An instrument panel, upon which appropriate flight data is indicated, is also introduced into the observers field of vision through the optical system.

Control of the optical elements is accomplished by means of a computer unit that in response to control input data and aerodynamic constant input data automatically solves the equations of flight in conjunction with the flight characteristics of the particular plane'chosen and transmits this data to a servo-amplifying system. This system amplifies the output signals from the computer unit to the proper proportionate quantities and transmits the amplified signals to appropriate instruments and motor drives throughout the device.

Further to produce the illusion of flying, proper noise conditions are provided by a noise simulator that is automatically controlled simultaneously with the other apparatus so that the pitch, frequency and volume of the noise vary as a function of air speed, propeller-pitch setting, and R. P. M. of the simulated engine. In addition, a mechanism is provided to produce the effects of stalling, operating as a function of the lift force and angle of. attack so that when these quantities are of values compatible with a stalled condition the pilots seat receives a shuddering impulse representing the flight instability of the plane at the moment, the control forces are diminished, and the controls accordingly become slack or sloppy.

The device is also provided with means to enable an instructor to observe the simulated effect through the optical system and to enable him to converse with the student pilot.

Detailed description Fig. 1 shows an area it! suspended from the overhead in an inverted position and containing models of terrain in sufficient detail to produce an effect of realism when viewed through the optical system to be described below. A curtain (not shown) can be provided around the periphery of the area Ii) and blended in to represent the sky.

The training device comprises an enclosed unit or cart I2 capable of controlled motionin one plane of the operating area (as by means of crab wheels [3), the interior M of which is sub- 3 stantially a replica of the cockpit of an actual airplane, insofar for example as the controls, instrument panel, seating of pilot, are concerned. A pilot, as l6, enters through a door, not shown, and is seated in a chair l8.

The instrument panel designated as 20 includes appropriate indicating instruments as 22 fordenoting such conditions as air speed, bank, rate of turn, flap position, angle of climb, rate of climb, altitude and apparent course. The panel 20 is illuminated by means of fluorescent lamps 24 or other lighting means of a suitable type.

The controls include rudder pedals 26, flap position leyer 28 cohtrols'tick '30 for ailerons and elevators, throttle lever 32, and control lever 34 for governing trimming tabs. I ,Ve'ntilationis provided as by means of a fan 36; An instructor csnt'onve'rse with the student pilot b"y 'in'eans "of a communication system provided ates. 7

Mounted upon the cart I2 is an optical viewing systm, generally des gnated as 40, remotely controlled by electro-mechanical means in such a anner that the optical components are alteredin their relative positions so as to produce an image of themodel T0 that simulates and transmits to the pilot "I'Bgseated within the mock cockpit, the illusion of seeing from the pilots enclosure of an airplane the actual view as would be seen from a real "plane in flying.

* Optical system The optical device 40, as seen in Fig. 1, includes a periscope 42 having rotatable head 44 containing a pitch-angle p'rism'and an objective-lens assembly, as will. be described below in connection with Fig-2. Light rays from 'the objective lens assembly are passed throughvarious optical elements, described below, and through a partly reflecting mirror 46 that reflects part of the rays to an instructors scope 48 and passes the remainder to a mirror 50 and thence to an observrs viewi'n g'he'ad'52. The instructors scope 48 is conveniently placed at, for example, a 90 angle to the main viewing head 52 and extends outside fo'f 'the cart I2 so that an instructor located on the 'du't'side "of the device can view the same i magejof themodel l0 -as the operator [6. A seat (flqt'shb'tvh) can be provided for the instructor if desired. The scope '48c'anbe telescoped for retracting theinstructors scope to within the confines-or the dev ce. W I

The'v ertic'al'tube of the 'perisco'pe 42 contains an optical collimating'systemenabling it to be 'ir'ie'c'lianically'telescoped within itself in response to control signals in order to retract the objective lens from the terrain so as to create the effect "of changin altitudes. I

, Ah'ima'ge of theinstr'u ment panel 29'is introduced intotheobservers view in its proper relative position by'means'ofa splitfield in the opticalsystem. v, N, H H The optical system is better understood by reference to Fig. 2, in whichis illustrated diagrammatic'ally the observers viewinghea'd 52, which .c'a nfb'e a conventional stereoptic binocular viewing head with adjustable interocular distance and independent focusing arrangement for each eye at eyepiece assemblies 54 into which the observer is (Fig. 1') looks. Front-surfaced mirrors 56 and tworight-angle prisms 58 and 6%) complete the viewing-headassembly. c

jTheiright-angle prisms 58 and 60 are so constructed.and'j'arranged as to 'allow an image of the instrument panerz'o (Fig 1) 'to be superimangle or elevation prism ti; mounted for rotation upon periscope head 4% about a horizontal axis perpendicular to the center line of sight of the optical system. Such rotation causes the center line of sight to be angularly displaced from a horizontal reference line perpendicular to the axis of rotation and said center line of Sight has its angular traverse remain in a vertical plane passing perpendicularly through the axis of rotation at the optical center line. Such rotation causes an apparent change in attitude, or angle at which the object is viewed. The image thus formed is in vertical alignment with the center line of the optical system. The apparent center of rotation of the image is coincident with the real center of rotation of the optical elements. h

Immediately below the elevation prism it is a stationary entrance pupil "H having an aperture of small diameter, as 'f ore'xample, in the order of 2 millimeters. The entrancepupil size to gain a depth o'f'con'ti'nuous focus for all objects appearing between the elevation prism it and infinity.

The exit pupils contained in objective-lens assemblies 54 and 82 are of the same diameter as the entrance pupil l I Also mounted in the rotatablehead M of the periscope 42 (Fig. fan objective-lens assembly l2 (Fig. 2). The objective-lens assembly 72 and pitch-angle prism it), including the housing, are so designed that the point at which the observers eye appears to be (i. 'e., at the axis of rotation of the'object prism), can be 'moved very'clo'se to the model being viewed. The assembly is also remotely controllable in rotation about the vertical axis as described above in connectio'n'with Fig. 1 so that an apparentch'ang'e in'heading in azimuth or turningcan be achieved without necessitating rotation of the cart I2. Such rotation is coordinated with the change in azimuth of the'car't crab Wheels and is prcp'erly compensated through 'a derotating prism i4, so that the image is not rotated at the binocular eyepiece54.

The derotating prism 14, which can be of the type known to the art as a dove or Schmidt prism, also effects the illusion of banking by'an ruption of the pilots field division normally occupied by the engine 'co'wling and instrument panel, isplaced between the objective lens assembly T2 and the dei'otatiilg "M. This mask is concomitantly and with'the prcperra'uo rotated so as to appear stationa'rywhenever rotation of the derotating prism Te occurs.

Following the derctatin'g prism "14 is a collimating doublet 80. Betweenthis 'andth'e'mirror 46 the system is telescoped to simulate changes in altitudes.

Mirror 46 is of a type that partly transmits 7 and partly reflects the light, enabling an instruct'o'r to view 'the 'relief map or model in through the scope 48' (Figl) by virtue of eyepiece assembly 82, appropriately placed reflecting mirrors 84 and collimating doublet 86. This system, as aforestated, can also be telescoped between the collimating doublet and the reflecting mirrorfor purposes of retracting into the device when not in use.

The light passing through the partly reflecting mirror 4% passes through a collecting doublet 88 and is reflected by appropriate mirrors 9!! (combined as mirror 50 in Fig. 1), through the right-angle prisms 58 and 60 of the viewing head 52, and thence to the observer l6 seated in the mock cockpit enclosure M, (Fig. 1).

A masking element 92, a plan view of which is shown in Fig. 4, having masking strips 94, is included in each eyepiece assembly 54 adjacent to the field lens of that assembly so that the view as seen by the observer It appears to be partly obstructed by structural members of an airplane cockpit as in a real plane. The instrumentpanel field of vision is superimposed in the area 96, corresponding to that portion of the main field of vision blocked by area 18 of mask 16 (Fig. 3), by means of the prisms, lens, and mirror assembly previously described.

Sewn-Amplifying System As stated above, the optical elements are controlled in response to the simulated control elements in the cockpit by means of an aerodynamic computer and servo-amplifying system.

' As indicated in Fig. 1, a computing unit 93, that can be electronic, mechanical or electromechanical, automatically solves the equations of flight by equating the input control signals of rates and positions of the throttle 32, stick 30, rudder 26, flaps 28 and other control equipment with the flight characteristics data of the plane and the aerodynamic variables, and solves for the resultant effects of all the variables, such as, air speed, angle of attack, bank, climb and dive, turn, rates of response to controls, forces required to operate controls, and the like. These computed data are then transmitted to a servoamplifying mechanism, generally designated as I00, that receives the input signals and amplifies them to the proper proportionate electrical quantities and transmitsthese data to appropriate instruments and motor drives of the device so that rotation and movement of the elements of the above described optical system are as described.

The servo-amplifying system consists of a plurality of any type of commercial servo-amplifiers, the adaption of which to the present application are readily apparent to those skilled in the art. A prime requisite of the system is amplification of the computer signals such that they can be used as accurate motor control. Each amplifier of the system receives signals from the device 93 and sends a properly amplified electrical quantity to a servo-motor I08 that rotates the periscope head 44 containing pitch-angle prism I0 and objective-lens assembly 12 about a vertical axis so that the operator l6 receives the illusion of a change in heading relative to the earth. The mechanical connection between the periscope head 44 and motor N33 is denoted by dashed line I I0. Derotating prism 14 and masking lens 16 are rotated simultaneously by means of mechanical connections at H2, H4 and H6 as explained in the above description of the optical system. A corresponding signal is transmitted direct from the computer 98 to an apparent-course indicator on the control panel 20 as by one of the lines I04, no amplification of the signal being necessary for operation of the indicating instrument.

Apparent course as used herein is defined as the angle measured in the horizontal plane, clockwise from the north, to the vertical plane containing the fore and aft or fuselage axis of the airplane. The apparent course can be angularly displaced from the actual course, or angle measured in the horizontal plane, clockwise from the north, to the vertical plane containing the flight path, by an amount depending on the instant flight conditions. Apparent course is indicated by the compass in both thetrainer and an actual plane.

A roll-amplifier H6 receives angle-of-roll data from computer 98, and sends an amplified electrical quantity to servo-motor in, which controls by mechanical connection 122 the rotation of the Schmidt or derotating prism 14 and mask 16 to produce theillusion of banking and rolling. This datum, correlated with pitchangle data in the computer 98, is sent direct through one of lines IE4 to a banking indicator on instrument panel 20. To effect a change in apparent course, motor Hi8 causes shaft. Hi] to rotate assembly 44 in azimuth. Such rotation alone would cause the image as seen by the observer through prisms 14 and 'ill (Fig. 2) to rotate about the optical aXis as well as the intended change in azimuth or shifting of the image laterally. Therefore, to nollify such erroneous rotation, differential H2 from shaft HE! causes rotation of gear H4, which in turn through a gear attached with derotatingprism 14 causes it to rotate in the same direction as assembly 44 but at twice the speed of assembly 44, thereby causing the image to be translated laterally without rotation. However, the rotation of prism 14 would also cause the image of the mask 16 to rotate at twice the speed of rotation of prism M. It is therefore necessary through gear H6 to rotate the mask #6 in the same direction as prism 14 but at one half the speed of prism 14.

It is obvious that when the angle of roll motor I20 alone operates Shaft I22 through the differential H2, the gears H4 and H6 will cause the prism 14 to be rotated at twice the speed of the mask 16 thereby causing rotation of the image of the object which is external to the optics without rotation of the image of the mask 16 which is in the optical system. This operation will of course not cause movement of shaft Hi).

It is obvious that both motors Hi8 and I20 may operate simultaneously with proper correlation of their separate functions.

A vertical-velocity or change-of-altitude amplifier I24 receives data from computer 98 and sends properly amplified electrical data to motor I26 that through mechanical linkage I26 telescopes or extends the optics, as previously described, to produce the illusion of changing altitude corresponding to the rate of dive or climb. Corresponding altitude data are sent direct from the computer 98 via one of lines 188 to an altitude-indicating instrument or altimeter on the instrument panel Appropriate data are also transmitted from computer 98 to an instrument for indicating the rate of climb.

A pitch amplifier its receives pitch-angle data from computer 98 and sends the properly amplified quantity to servo-motor i322 which by mechanical linkage it rotates the pitch-angle prism is (Fig. 2) about a horizontal axis so to simulate a proper pitch angle as the airplane apparently climbs or dives. A corresponding signal is sentdirect from computer 58 via one of lines Hit to an angle-oi-climb indicating instrument on the panel 28.

A horizontal-speed amplifier 535 receives Velocity data from computer at and sends the corresponding amplified electrical data to servomotor lfiii that drives, by means of mechanical linkage the several crab wheels is mounted on the chassis of the cart E2 so as to provide a movement of the cart that corresponds to the horizontal speed of the craft along its line of flight. Properly correlated vertical and horizontel-velocity data are also provided, via one of lines directly from computer 98 to an airspeed indicator on instrument panel 29.

A direction or actual-course amplifier Hi2 receives actual-course data from computer 98, and sends a corresponding electrical signal to servomotor I 35, that through mechanical linkage S lt, controls the direction of the crab wheels I3 so as to control the direction of movement of the cart it so that a simulation ofchange of course of the fiight path relative to the earth is provided.

A control-loading amplifier M5 receives a sig nal from computer 93 that varies as a function of air speed and accordingly provides an amplified electrical control quantity to servo-motor 55 that through mechanical linkages I52, E55 and I55 decreases and increases-the force opposing operations of the rudder 2%, stick 3t, and trim tab control 35. Th trim-tab control 3 3 functions to shift the neutral-load position of the other controls and 3% such that the apparent trim condition of the plane is altered.

In order to produce noises of proper pitch, frequency and volume a conventional noise amplifier E56 is provided and controlled as a func.

tion of throttle setting, as by mechanical linkage 158, and as a function of angle of pitch by means of electrical control signals from amplifier through connection shown at 168.

Computer 83 also provides control data as at.

-ments to the power. source.

Appropriate limit stops (not shown) are provided to confine the cart unit l2 to the boundaries of the deck upon which it moves, and toprevent :theperiscope from over-extending andcrashing' into the model or retraction beyond the limit of the optical system.

Acre-dynamic computer .ments of the present flight trainer and related .devices.

The function of the aerodynamic computer unit is to connect controls and optical illusion mechanism in the proper manner. Its inputs are control displacements; its outputsare angles and velocity components, specifying at any time the resulting attitudes and motion along the flight path of the airplane.

In order to simplify the description of the input and output quantities of the computer elements symbols and terms are used throughout as defined below:

Flight path-The actual path or" the center of gravity of the airplane.

X-axis-Fuselage axis or fore-and-aft axis through the center of gravity of the airplane.

Y-axisWing axis or-the axis through the center of gravity parallel .to a line connecting the wing tips of the airplane.

Z-axis-Axis through the center of gravity and perpendicular to both the X- andY-axes.

P-Angle of climb or angle between the Y-axis and the horizontal plane measured in the vertical plane'thlough the X-axis.

P1-Angle of pitch or angle through which the fuselage or X-axis must be rotated about-the wing or Y-axis in the XZ plane in order to become horizontal.

Rotation about the wing axis is-termedpitch- .ing. That part of which is due to pitching alone will be denoted .by

in d6 Pia-Angle of pitch of .flight path or the :angle between the flight path and the horizontal plane measured infthe plane containing the flight path and perpendicular to the "X-Y 'plane.

(ZP,, dt

pitching alone.

. I denotes thatpart of dP which results from R-Angle of rollor the angle through which the B-Actual course or the vertical projection to the earth of the line of flight. The direction of such projected line is the angle measured in the horizontal plane clockwise from the north to the vertical projection of the line of flight on HTE horizontal plane.

Be-Apparent course or the vertical projection to the earth of the X-axis. The direction of such projected line is the angle measured in the horizontal plane clockwise from the north to the vertical projection of the X-axis on the horizontal plane.

T-That part of T due to turning alone.

T'Angle of turn or angle through which the fuselage must be rotated about the Z-axis in order to attain a predetermined heading.

T -Angle of yaw or angle of rotation of the fuselage about the Z-axis necessary to make the XZ plane contain the flight path.

T -That part of T due to a deflected position of the rudder.

T\V-That part of T due to force on right wing as a resultant of lateral movement of the stick.

A-Angie of attack or the angle between the flight path and the XY plane measured in the plane containing the flight path and perpendicular to the XY plane.

AoThat part of A due to fore and aft displacement of the stick=KSs.

Al -Increase in the angle A due to use of flaps.

F-Forces acting upon the airplane.

W-Weight of the airplane.

F'1-The lift force acting perpendicular to the wind axis and the directionof motion.

Fer-Drag force acting aft along the flight path.

FeThrust force developed by the propeller, acting forward along the fuselage.

Fr-Resu1tant force acting forward along the flight path.

FuResultant force perpendicular to the wing "axis and the direction of motion.

Fw-Resultant force along the Y-axis.

Ce-Percent of full throttle=KSe.

CdCoefiicient of drag.

Clo- 0061 1166111; of lift due to wings.

CnC'oefflcient of lift due to flaps.

CiTotal coefficient of lift (Cz=Cz0+Cz (is-Coefficient of roll=KSl-.

Ctr-006fil0i6ilt of yaw due to rudder=KSa (Ii-Total coefiicient of yaw.

Sit-Fore and aft displacement of stick in degrees. I

SjFlap control displacement in degrees.

SiLatera1 displacement of stick in degrees.

St- RUGGBI pedal displacement in degrees.

Se -Throttle control displacement in degrees.

VAirspeed along flight path.

VhI-Ior izontal componentof air speed.

VvVertical component of air speed.

M-Mass of airplane.

I-I'-A1titude of airplane above sea level.

e-Density of air.

K--All constants.

The quantities required as computer outputs for controlling movement of the cockpit and optical elements of the flight-simulating device of this invention are angular components P representative of the angle of climb, R representative of the angle of roll, and Be representative of apparent course, for the airplanes attitudes, and Vs representative of horizontal velocity, Vv representative of vertical velocity, and 13 representative of the actual course, for

:the motion of the airplanes center of gravity representative of rate of turn, sin Rb representative of the angle of bank, and V representative of air speed, are required. Output quantities Fu, representative of lift force upon the wing and, A, representative of angle of attack are also required in order to operate the stalling mechanism. Thus the total output quantities are P, R, B, :30, V, Vh, H, SJ, dT and sin Rb.

On the diagram Fig. 5, and in the following description rates are written without the dt for the sake of brevity, e. g.,

appears as dA.

The inputs to the computer are KS: or C: representative of lateral displacement of the stick, KS8. or A0, representative of fore and aft movement of the stick, KSt or Ca representative of rudder displacement, KS8 or Ce representative of throttle control displacement, S; representative of flap-control displacement and time t. The value of K in each of the above instances varies in accordance with the particular control displacement; Thus, as will be more fully explained below, the value of K for a particular control setting can be supplied by a cam or other element designed in accordance with wind-tunnel 'data for the particular control surface and airplane to be simulated, and actuated by a shaft or other 'means from the control element. In

addition to these inputs the weight W. mass M of the airplane, and other aerodynamic constants are taken into consideration in certain of the computer elements. The value of such constants depends upon the particular airplane it is desired to simulate.

As indicated in Fig. 5, multiplier 200 multiplies a quantity Cr set up by lateral movement of the control stick, with an input quantity V representative of airspeed. The operation of the multiplier element 200 is based on the equation, well known in the art, that rolling moment is equal to the algebraic sum of the lift moments acting on the plane about its longitudinal axis through its center of gravity. This quantity is also equal to the coefficient of roll times the velocity. The

coeiiicient of rollvaries as a function of the mean or average angle that the movable control surface makes with the corresponding fixed surface. In

the multiplier 200 roll coefficient for theinstant angle of the movable control surface can besupplied by means of a mechanical or electrical cam, designed in accordance with wind-tunnel data for the particular plane to be simulated to represent the variable roll coefiicient, and actuated by the lateral displacement of the control stick. The output of the multiplier element is thereby representative of the rolling moments inherently present for successive differences of control displacement and velocity.

The output rate of roll dRs is added by an adding mechanism at 202 to an additional rate of roll dBc sin P giving an output total rate of roll 01R. that is integrated with respect to time t by integrating mechanism 204 to provide output quantity R. j

The time input t to the integrating mechanism angle of roll, is sent to a transmitter 206 that sends an electrical signal to roll amplifier H8 (Figure 1).

As aforestated, the computer elements, i. e., multipliers, etc. can be either mechanical, electromechanical or electronic. If mechanical elements are used throughout the computing system, the transmitter units can be of any type conventionally used for coupling mechanical and electrical equipment such as those known to the trade under the. names of Selsyn, Autosyn or Synchro units, or the coupling can be directly mechanical to servo-amplifier controls.

The input quantity A or KSE, due to fore and aft movement of the stick, is added to a quantity A, representative of the angle of attack, by adding mechanism 208, providing an output dA that in turn is provided as an input to integrating mechanism 2E0. The quantity 01A is integrated by mechanism 2! ii with respect to time, t, to provide the quantity A used in adding mechanism 208, above.

The quantity M1 is also provided to adding mechanism 212 where it is added to a rate dPa to provide an output dPr that, in turn, through follow-up mechanism 2M, is introduced as an input to. a component solver 215. Component solver 2 I 5 also receives quantity R as an input and provides outputs CZ'Pz' sin R and dPr cos R. One of the output rates from component solver 215, dPr cos R, is added by adding mechanism 2 I 6 to a rate dT sin R to give an output dP that when integrated by integrating, mechanism 218 provides output quantity P, that is sent to a transmitter 220 for transmission to pitch-angle amplifier I (Fig. 1). The quantity P is also sent to a transmitter 222 for transmission to an angle of climb indicating instrument on panel 20 (Fig. 1).

The rudder input quantity KSt or Cm as determined by a cam unit for the instant rudder displacement is added algebraically to the lateral stick input Cr by addin mechanism 223 that provides an output quantity Ct equal to Ora-Km.

Thus lateral stick input is linked with rudder input; use of the stick for rolling right (left) wing down automatically sets up an angle of yaw by actuating the left (right) rudder making it necessary for the student pilot to apply right (left) rudder pedal if he wants to make a proper turn (without angle of yaw, i. e., without slip or skid). The use of rudder alone (no movement of the stick) sets up an angle of yaw proportional to rudder pedal displacement and airspeed. Thus the rudder can be used either to set up or eliminate angle of yaw. The rudder also sets up a small rate of turn dT that is taken into consideration in the computer elements to be described below.

The output'quantity Ct from adding mechanism 223 is multiplied with the airspeed V by multiplier 224 to provide an output that is added to Ty by adding mechanism 226 to give cZT The rate dT is input to integrating mechanism 228 where it is integrated with respect to time t to provide the quantity Ty input to adding mechanism 226.

The quantity Ty is also input to mechanism 230 providing the rate dT' equal to KTv that is input to mechanism 232 where it is added to a rate dTw, representative of the rate of turn clue to lifting force upon the Wings. This sum 12 is added to dTy by mechanism 23:: providing the total rate of turn dT, i. e., equal to The rate dT is amplified by follow-up mechanism 235 and sent to a rate-of-turn transmitter 23'! for transmission to one of the indicating instruments on panel 23 (Fig. 1). Rate dT is also supplied as an input quantity to component solver 238 that receives R as its other input quantity and provides dT sin R and dT cos R as outputs. The first of these outputs dT sin R is supplied to adding mechanism 2I6 as aforementioned. The second output dT cos R is added by mechanism 246 to the other output dPr sin R of the component solver 2l5 providing the rate dT cos R-dPr sin R that is supplied to multiplying mechanisms 242 and 244 that also receive the quantity P as inputs. Multiplier 2'42 multiplies dT cos RdP1- sin R tan P to provide the rate dBc sin P" used in adding mechanism 262. The other multiplier 244 multiplies dT cos R-dPr sin R sec P providing a rate dBc that is integrated with respect to t by integrator 2 46 giving the quantity Be. Data representative of this quantity is transmitted by transmitter 2&3 to apparent course ampli- 5 fier I06 (Fig. 1) and by transmitter 256 to an apparent-course indicator on instrument panel 20 (Fig. 1)

The output quantity Ty from integrator 228 is also supplied as an input to a component solver 252 that receives the quantity R as another input and provides output Ty sin R and T3 cos R. The latter output quantity Ty cos R is added by mechanism 254 to one of the output quantities A. sin R from a component solver 256 that receives as input components R and A. The output from adding mechanism 254 is A sin R-Ty cos R. This quantity is multiplied with the quantity P by multiplier 258 to provide an output that, when added to apparent course quantity Be at adding mechanism 255, provides an output B representative of the actual course relative to the ground. Data representative of the quantity B is transmitted by transmitter 232 to 'actual course amplifier I42 (Fig. 1 7

By following through the computer elements it can be seen that apparent course and actual course data are initiated by both stick and rudder controls, and that this data is based on actual flight characteristics as determined by wind tunnel data and as introduced into the computer system by means of the cam units previously described. Thus the final course data provided by the computer unit is representative of the turning moments inherently present for the particular airplane for successive differences of control displacement and velocity.

Throttle input KSe or Ce is supplied to a functional multiplier 264 that multiplies a determined function of Ce with a determined function of airspeed V to provide an output quantity Fe. The determined function of Ce is representative of the percent of full horsepower available for the particular throttle opening and the determinedfunction of airspeed V is representative of propeller developed thrust at full horsepower so that the product Fe or total developed thrust is obtained from percent H. P. times thrust at full H. P. This is accom- -cator on the instrument panel 29 (Fig. 1).

13 plished within the computer element 264 by means of mechanical or electrical cams the design of which is based on wind-tunnel data for the particular airplane to be simulated. The cam for percent engine horsepower is actuated by a shaft or other means from the throttle control and the cam for thrust at full horsepower is actuated by a shaft or other means representative of velocity.

The quantity Fe is amplified by follow-up mechanism 266 and sent to component solver 268 that receives as its other input quantity the angle of attack data A and provides outputs Fe cos A and Fe sin A. The latter quantity Fe sin A is added by adding mechanism 210 to a quantity W cos R cos P from a component solver 212 that receives the quantities W, R and P as inputs and that has the quantity W inherently available as a constant multiplying factor to provide an output quantity Fe sin AW cos R cos P.

V This output is added by mechanism 2'14 to lift force quantity F1 provided by multiplier mechanism 216 that multiplies velocity data V with C1. The output of adding mechanism 214 is the quantity Fu VdPa. The quantity Fu is utilized in conjunction with a quantity A to operate standard control switches illustrated diagrammatically at 28s for the stalling mechanism. The quantity VdPa is multiplied by the reciprocal of velocity V at reciprocal multiplier 282 to provide the output dPa that is provided as an input quantity to the adding mechanism 2l2.

The other output of component solver 212, W sin R cos P or Fw, is supplied to the reciprocal multiplier 285 Where it is multiplied with the reciprocal of the velocity to provide the rate dTw that is utilized in adding mechanism 232.

The other output from component solver 268, Fe cos A, is added by mechanism 286 to drag force Fa, providing an output quantity Fe cos A-Fe that is in turn added to quantity W sin(P-A cos .R-T-y sin R) by mechanism 288 to provide dV. The rate (W is integrated with respect to time t by integrating mechanism 299 to provide airspeed quantity V. The quantity V is supplied to an airspeed transmitter '292 for transmission of representative electrical data to an appropriate indicating instrument at panel (Fig. 1) and to the various multipliers and component solvers as described above.

The other output quantities of component solvers 252 and 256, T sin R and A cos R, are added by mechanism 29% providing anoutput quantity T sin RA cos R that is, in turn, added by mechanism 296 to pitch angle P. The resultant quantity is supplied to a cam unit 298 which multiplies a function of this input quantity with weight W to a provide the output W sin (PA cos R---T-y sin R) utilized in adding mechanism 288. The output from adding mechanism 296, is also supplied to component solver .300 which solves this input with airspeed input V to provide vertical and horizontal velocity components Vv and Vh, respectively, as outputs. The output Vv is integrated with respect to time t by integrator 302 to provide altitude data H which is sent by transmitter 3% to the changeof-altitude amplifier lZd (Figl), and by transmitter 306 to an appropriate altitude indi- Vertical velocity data Vv is also sent to transmitter 301 for transmission to an appropriate rate of climb indicating instrument on' the instrument panel 20 (Fig. 1).

The horizontal velocity componentVh is inte- 7 14 grated with respect to time t by integrating mechanism 303 to provide change of distance data relative to the ground, which data is transmitted by transmitter 3H3 to horizontal speed amplifier I (Fig. 1).

A flap-control motor 3E9 provides flap-displacement datum S; which is supplied to a transmitter 312 for transmission to an appropriate device for indicating flap position on the instrument panel'zn (Fig. l). The quantity S is also supplied to a mechanism at 3M where it is divided into quantities C1 indicative of lift due to flaps, and Aj, indicative of increase in A due to flaps. The quantity A is added by adding mechanism 3R6 to quantity A, supplied from mechanism 2 l0, providing an output A+Ai that is representative of a drag coefiicient determined by a cam function in unit 2l8 that is multiplied with velocity V in multiplying mechanism Iii-8, providing the output Fa utilized'in adding mechanism 286.

. Thev multiplier element 3H3 operates on the principle, well known in the art, that drag force acting on an airplane wing is equal to the product of a constant times the coefficient of drag times the velocity squared. The cam unit of the element MB is thereforedesigned to represent a variable coefilcient of drag in accordance to wind-tunnel data. The cam is actuated by a shaft, the positioning of which is representative of A+Agi or the angle at which the mean or average chord line of the wing meet the relative wind and known as angle of attack. of element SIB therefore is representative of the drag forces inherently present for successive values of angle of attack and velocity.

The quantity A from mechanism 2 l 0 is also supplied to a cam unit 320 that resolves this value into lift data C10 due to the position of the wings. The cam of this element is representative of windtunnel data of a variable coeflicient of lift and is actuated by a shaft or other means representative of angle of attack. The quantity C10 is added by adding mechanism 322 to the quantity 01 from mechanism 3! to provide the quantity C1 utilized in multiplying mechanism 216. The mechanism multiplies C1 by the velocity squared to provide quantity F1 representative of lift force inherently present for the instant value of velocity and angle of attack.

For a more complete description of the theory of operation of the computer elements, including derivation of the equations upon which the computer element inputs and outputs are based, reference is hereby made to U. S. Navy Publication entitled Theory of the Aerodynamical Computer by Harold P. Wicklund and Fritz Steinhardt.

- Operation An example of one manner in which the flight trainer of this invention can be operated is given below. v

It will be assumed that all optical elements a are in proper alignment so that the observer views The output 15 earphones of the intercommunication system 38. He then turns on a switch (not shown) cqnneote ing the power supply with the amplifiers and motor elements as previously described.

The device is now ready for the simulated take on". All handling of the flight controls is identical to that in the operation of an actual airplane. As the throttle is opened the noise simulator produces appropriate engine noises. As the plane supposedly moves forward the mock cockpit moves forward on its crab wheels I3. When the control stick 30 is pulled back and the plane apparently climbs, the periscope head 24 retracts accordingly and the pitch angle or elevation prism 'IEI rotates about its horizontal axis away from the model so that the image formed of the model changes to provide the illusion of climbing to the observer. After the plane is supposedly in flight the operator can manipulate the controls as desired to bank, dive, climb, turn or roll, the cockpit assembly and optical elements moving in accordance with control data from the computer so that from the standpoint of his visual observation the operator appears to be actually completing the desired maneuvers. When the control stick is pushed forward and the plane supposedly dives, the elevation prism rotates about its. horizontal axis toward the model and the periscope is extended toward the model. When the control stick and rudder are moved in a manner to produce a coordinated turn the crab wheels 13 and periscope head 44 turn relative to the cart but not relative to each other and masking element 76 and derotating prism 14 also have concomitant rotation in the proper relation to produce the illusion of coordinated banking and turning without slip or skid (i. e. without yawing). When a non-coordinated turn resulting from control displacements exists, the periscope head 44 and crab wheels i3 are also rotated relative to each other by an amount (angle) representative of the magnitude of yaw (i. e. slip or skid) for each particular condition. In response to proper data from the computer unit the derotating prism 14 and mask 76 rotates to the right or left to produce a rolling illusion. A number of such movements can take place at the same time to simulate the various conditions encountered in actual flight maneuvers.

The instantaneous flight conditions at any point in the flight are indicated by the indicating instruments upon the instrument panel. Thus the observer can check conditions by glancing at the image of the instrument panel.

The operator can cut off the power supply at any time during the mock flight and later'resume operations at the same point by again closing the power switch.

An instructor observing the model through the scope 48 can direct operations through the intercommunication system 33 or can discuss flight conditions with the student seated within the device.

The flight simulating methods and device of this invention provide valuable aids to the art of flying and flight instruction.

It is to be understood that various modifications and changes may be made in this invention without departing from the spirit and scope thereof as set forth in the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. Flight simulating apparatus comprising model of terrain, a mock cockpit assembly ineluding control elements mounted for movement With respect to said model, an optical viewing system including a pitch angle prism and an objective lens mounted upon said cockpit whereby an observer seated in said cockpit may view an image of said model, means for extending and retracting said optical elements with respect to said model in response to control signals corresponding to control data to simulate changes in altitude, means responsive to control signals corresponding to control data for rotating said optical elements in a plane parallel to that of said model to simulate changes in course, means responsive to control signals corresponding to control data for rotating said pitch angle prism in a vertical plane with respect to said model to simulate change of attitude, and means responsive to control signals corresponding to control data for moving said cockpit unit with respect to said model to simulate horizontal velocity, whereby to alter said image as though said image were moving with respect to said model to produce the illusion of flight.

2. Flight simulating apparatus comprising a model of terrain, a mock cockpit assembly including control elements mounted for movement with respect to said model, an optical viewing system mounted on said cockpit whereby an observer seated in said cockpit may view an image of said model, computer means associated with said cockpit assembly for correlating flight characteristics data with control data from said control elements, means for converting the resultant data into electrical signals, means for amplifying said electrical signals, and means responsive to said amplified electrical signals for controlling the movement of said cockpit and the movement of the optical elements of said optical system, whereby to alter said image as though said image were moving with respect to said model to produce the illusion of flight.

3. Flight simulating apparatus comprising a model of terrain, a mock cockpit assembly including control elements mounted for movement with respect to said model, an optical viewing system mounted on said cockpit whereby an observer seated in said cockpit may view said model, said optical viewing system including a retractable periscope having a rotatable head, an elevation prism and objective lens assembly in said rotatable head, said elevation prism being mounted for rotation within said head about an axis perpendicular to the optical center line of said viewing system, rotatable dove prism means in said periscope for governing rotation of the image of said model about the optical axis of said viewing system, means for correlating control data from said control elements with flight characteristics data whereby to provide signals corresponding to apparent course data, actual course data, pitch angle data, roll data, altitude data and horizontal velocity data, means responsive to said apparent course signals for controlling rotation of said periscope head, means responsive to said actual course signals for controlling the direction of movement of said cockpit assembly, means responsive to pitch angle signals for controlling rotation of said elevation prism relative to said periscope head, means responsive to roll signals for controlling rotation of said dove prism, means responsive to altitude signals for controlling the retraction of said periscopeand means responsive to said horizontal velocity signals for controlling the speed of movement of said cockpit assembly relative to said model, whereby to control the movement of said cockpit assembly and the above stated optical elements of said viewing system mounted thereon such that the relative movement of the model viewed through said viewing system produces the illusion of flight to the observer.

4; Flight simulating apparatus comprising a three-dimensional model of terrain, a mock cockpit assembly including control elements mounted for movement with respect to said model, an optical viewing system mounted on said cockpit whereby an observer seated in said cockpit may view an image of said model,said optical viewing system including an elevation prism for collecting raysfrom said model and mounted for rotation about an axis perpendicular to said model and also for rotation about an axis perpendicular to'the center line of said viewingsystem, an objective lens assembly in receiving relation to said elevation prism, rotatable prism means in receiving. relation to said objective lens for rotating said image about its center, optical collimating means for paralleling the rays from said rotatable prism, a, viewing head for projecting the image into the field of vision of the observer, means for correlating control data from said control elements with flight characteristics data whereby to provide signals corresponding to apparent course data, actual course data, roll data, altitude data, and horizontal velocity data, means responsive to said apparent course signals for controlling rotation of said elevation prism about said axis perpendicular to said model, means responsive to actual course signals for controlling the direction of movement of said cockpit assembly, means responsive to pitch angle signals for controlling the rotation of said elevation prism about said axis perpendicular to the optical center line, means responsive to roll signals for controlling the rotation of said rotatable prism, means responsive to altitude signals for retracting and extending said optical system with respect to said model, means responsive to said horizontal velocity signals for controlling the speed of movement of said cockpit assembly relative to said model, whereby to control the movement of said image of said model so as to produce the illusion of flight to the observer.

5. Flight simulating apparatus comprising a model of'terrain, a cockpit assembly having control elements including a control stick, an optical viewing system including a rotatable prism whereby an observer seated in said cockpit may view said model, means for correlating control data with flight characteristics data to provide velocity signals, means for multiplying data due to the lateral motion of said control stick with said velocity data to provide rate of roll data, means for integrating said rate of roll data with respect to time to provide angle of roll signals, means for amplifying said angle of roll signals, and means responsive to said amplified signals for controlling the rotation of said prism whereby to provide an image of said model corresponding to the instant simulated angle of roll condition.

6. Flight simulating apparatus comprising a model of terrain, a cockpit assembly having control elements including a control stick, an optical viewing system including a rotatable prism, whereby an observer seated in said cockpit may view said model, means for correlating control data with flight characteristics data to provide velocity signals,'means for multiplying data, due to the lateral motion of said control stick with said velocity data to provide rate of roll data, means for correlating control data with flight characteristics data to provide additional rate of roll data due to simulated pitching and turning conditions, means for adding said first mentioned rate ofroll data to said second mentioned rate of roll data to provide total rate of roll data, means for integrating said total rate of roll data with respect to time to provide angle of roll signals, means for amplifying said angle of roll signals, and means responsive to said amplified signals for controlling the rotation of said prism whereby to provide animage of said model corresponding to the instant simulated angle of roll condition,

7. Flight simulating apparatus comprising a model of terrain, a cockpit assembly having'control elements including a control stick, an optical viewing system including a rotatable prism whereby an observer seated in said cockpit may view said model, means responsive to lateral movement of said control stick for providing coefli- I cient of roll data in accordance with wind tunnel data for the instant average angle that the movable control surfaces of the simulated plane make with the corresponding flxed surfaces for each position of the control stick, means for correlating control data with flight characteristics data to provide velocity data, means for multiplying said coefiicient of roll data with said velocity data to provide angle of roll signals, and means responsive to said angle of roll signals for controlling the rotation of said prism whereby to provide an image of said model corresponding to the instant simulated angle of roll condition.

8. Flight simulating apparatus comprising a model of terrain, a movable cockpit assembly having control elements including a throttle, an opti cal viewing system mounted upon said cockpit whereby an observer seated in said cockpit may view said model, means responsive to said throttle for providing data representative of the percentage engine horsepower available for the instant position of said throttle, means for providing data representative of thrust force at full engine horsepower for the instant simulated velocity, means for multiplying said percentage data with said thrust force data to provide instant propeller thrust force data, means for correlating said instant propeller thrust force data with other instant 'fiight characteristics data to provide ve locity data, means for resolving said velocity data into vertical and horizontal component signals, and means responsive to said horizontal component signal for controlling the velocity of horizontal movement of said cockpit assembly with respect to said model. i

9. vFlight simulating apparatus comprising a model of terrain, a movable cockpit assembly, on

optical system mounted thereon whereby an observer seated in said cockpit may view said model, a computer for correlating control data from said cockpit with flight characteristics data to provide output signals for controlilng the movement of the optical elements of said optical system to produce an illusion of flight, said computer including means for providing coeflicient of lift data in accordance with wind tunnel data for the instant angle of attack of the simulated plane, means for multiplying said coeffiicent of lift data with the square of the instant velocity to provide lift force data, means for correlating said liit force data with other flight characteristics data,

, 1'9 "and means for applying the resultant output signals that correspond to the data to control said optical elements.

10. Flight simulating apparatus comprising a model of terrain, a. movable cockpit assembly, an optical system mounted thereon whereby an observer seated in said cockpit may view said model, a computer for correlating control data from said cockpit with flight characteristics data 'to provide outputsig'nals for controlling the movement of the optical elements of said optical system to produce an illusion of flight, said computer including means for providing coefllcient of drag data in accordance with wind tunnel data for the instant angle'of attack 'of the "simulated'plane. means for multiplying said-coefiicie'nt of drag data with the square of instant velocity to provide 'dr'ag force data, means for correlating this data with other flight characteristics data, and means "for applying the resultant 'oiitput'si'g'nal's corresponding to the data to control said optical elements. H

HAROLD P. WICKLUND.

, REFERENCES CITED "The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 25 Number 7 Name Date Link, Jr. Nov. 23, 1937 Koster July 4, 1939 Ocker Apr. 13, 1943 Crane Aug. 17, 1943 Hill Sept. 14, 1943 Dehmel a Jan. 2, 1945 White vApr. 24, 1945 Gumley Feb. '26, 1946 Jones Dec. 31, 1946 Albert Oct. 14, 1947 Kail Apr. 6, 1948 Kittredge Apr. '6, 1948 Link May 25, 1948 Delim'e'l Ju'ne22, 1948 Germanton Feb. 1. 1949 Lukac's May 31, 1949 Dehmel July 5, 1949 'Dehmel 'Oct. 18, 1949 Dehmel Jan. 10, 1950 Hayes .June 6, 1950 FOREIGN PATENTS Country Date Great Britain 'Feb. 28, 1946 

